Supercapacitor breakthrough suggests EVs could charge in seconds but with a trade-off

Supercapacitors may be providing an alternative to electric-car batteries sooner than expected, according to a new research study. Currently, supercapacitors can charge and discharge rapidly over very large numbers of cycles, but their poor energy density per kilogram —- at just one twentieth of existing battery technology — means that they can’t compete with batteries in most applications.

That’s about to change, say researchers from the University of Surrey and University of Bristol in conjunction with Augmented Optics. They have announced a breakthrough in supercapacitors, which are said to be between 1000 and 10,000 times more powerful than equivalent lithium-ion batteries and considerably quicker to recharge. However, they lack the storage capacity found in traditional automotive-grade lithium-ion batteries used in today’s electric cars. But Jim Heathcote, chief executive of Augmented Optics Ltd and Supercapacitor Materials Ltd, says consumers would likely still be happy with the trade off by having faster charging times. “A lot of people would be more happy with a half the range of a 300-mile, lithium ion-batteried EV, but a fast charging time”. If their research can be translated into the consumer market, EVs could re-charge in a time quicker than filling a vehicle with a tank of gasoline.

Tesla CEO Elon Musk has remarked in the past about the use of supercapcitors in electric vehicles, “If I were to make a prediction, I’d think there’s a good chance that it is not batteries, but super-capacitors.” The recent research could be a first sign that Musk’s prediction from five years ago could one day come to fruition.

Why a combination of batteries and supercapacitors is essential to a sustainable future

In the next few decades, fossil-fueled cars and home-heating systems will need to switch to electric power to avert catastrophic climate change. Electricity has tremendous benefits but also one significant drawback: it’s relatively difficult to store in a hurry. Batteries can hold large amounts of energy, but they take hours to charge. Capacitors are a solution to this dilemma, as they charge nearly instantaneously.

A supercapacitor solves the problem of storing a reasonable amount of energy for a relatively short period of time. Supercapacitors have been typically used as energy reservoirs to stabilize power supplies to electrical and electronic equipment. But supercapacitors can also be connected to batteries to regulate the power they supply. However, up until this point, they have only been able to store minuscule amounts of energy.

To truly have a feasible electric-powered lifestyle in which we can store and release large amounts of energy very quickly, we need efficiency in both batteries and supercapacitors. Supercapacitors help to solve the “energy versus power” conundrum. “Energy” is the capacity to do work. In physics, work is the act of exerting a force over a distance. While energy measures the total quantity of work done, it doesn’t say how fast you can get the work done. “Power” is the rate of producing or consuming energy. Supercapacitors can bridge that divide and solve the inherent trade-off between EV energy and power.

Dr. Brendan Howlin of the University of Surrey said: “There is a global search for new energy storage technology and this new ultra-capacity supercapacitor has the potential to open the door to unimaginably exciting developments.”

They hope to have a working prototype by spring 2017. “We are now actively seeking commercial partners in order to supply our polymers and offer assistance to build these ultra-high-energy density storage devices,” said Heathcote. In current form, the high energy density supercapacitors could make it possible to recharge mobile phones, laptops, or other mobile devices in just a few seconds.

A fleet of supercapacitor-equipped buses is already in use in China, although they do not achieve the range proposed by the Surrey research team.